This paper describes the evolution of Canadian air quality since the early 1970s and discusses the scientific question of whether current air pollution levels are a threat to human health. It then describes the existing structure of Canadian air-pollution policy, including the new focus on ultrafine particles and the introduction of Air Quality Indexes. It concludes by outlining some general principles that should guide policy-makers for developing future air-pollution legislation.

Air quality in Canada has substantially improved since the 1970s and at least some of this improvement can be attributed to the detailed, extensive system of legislation currently in place to control air pollution. New initiatives in air pollution legislation, including the proposed Clean Air Act , should take into account the fact that air quality is already regulated and that pollution has already been substantially reduced. This paper describes the evolution of Canadian air quality since the early 1970s and discusses the scientific question of whether current air pollution levels are a threat to human health. It then describes the existing structure of Canadian air-pollution policy, including the new focus on ultrafine particles and the introduction of Air Quality Indexes. It concludes by outlining some general principles that should guide policy-makers for developing future air-pollution legislation. It argues that policy-makers should begin by focusing on giving people access to objective, accurate, and up-to-date information on pollution levels and trends, as well as helping them to understand the existing structure of air-pollution regulations that affect their regions. It also argues for flexible, locally-tailored initiatives that give people more direct say in the level of environmental quality they enjoy, and for more exploration of the use of emission-pricing instruments.